81 lines
1.5 KiB
ArmAsm
81 lines
1.5 KiB
ArmAsm
;drawing line from 2 cordinates
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.proc line
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testing:
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;# (X_pos, Y_pos) #
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;# * #
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;# * #
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;# * #
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;# (X_end, Y_end) #
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;
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; NOTE THAT X_pos <= X_end and line is going downwords max 45deg!
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;Not values but register position in memory
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X_end = $04
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Y_end = $05
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X_pos = $FC
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Y_pos = $FB
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dy = $06
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dx = $07
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D = $08
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;Set values
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LDA #$00
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STA $FD ; for pixel_draw
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;example values ~~~~~ SHOULD BE PRECOMPILED
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LDA #$00
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STA X_pos
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STA Y_pos
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LDA #$50
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STA X_end
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STA dx
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LDA #$40
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STA Y_end
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STA dy
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LDA #($40 + $40 - $50 )
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STA D ; = 2*dy - dx
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; ~~~~~~~
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for_x:
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jsr pixel_draw
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LDY D ; FOR DEBUG
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; If D <= 0 then: skipp
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LDX D;
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DEX
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BMI case_2
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case_1:
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INC Y_pos
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;D = D_before -2*dx
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LDA dx
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ROL A
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TAX
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LDA D
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STX D ; D = -2*dx, A = D_before
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SEC
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SBC D ; A = D_before -2*dx
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STA D;
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jmp last
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case_2:
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;D = D + 2*dx
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LDA dx
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ROL
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CLC
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ADC D
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STA D
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last:
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CMP #$00
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; increment x untill x == large
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INC X_pos
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LDA X_pos
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CMP #199
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BEQ end
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JMP for_x
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end:
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jmp testing
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.endproc
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